Senate Democrats are on the cusp of securing enough GOP votes to break a filibuster next week on the bipartisan budget, temporarily ending the fiscal crises that have dominated Washington for the past several years.

With 53 Democrats and two independents expected to back the measure, four Republicans — John McCain of Arizona, Susan Collins of Maine, Jeff Flake of Arizona and Richard Burr of North Carolina — said that they would vote to cut off debate on the budget, putting proponents just one vote shy of advancing the measure to final passage.

Several additional GOP senators signaled Friday that they may also vote to advance the deal, including Sens. Bob Corker of Tennessee, Lisa Murkowski of Alaska and John Hoeven of North Dakota, giving proponents new confidence that a messy and acrimonious first session of the 113th Congress appears close to ending just before Christmas.

The Senate is poised to hold the critical procedural vote on the budget bill on Tuesday. And several GOP senators said while they may oppose the underlying bill, they would join with Democrats to advance the measure for a final up-or-down vote.

“I’m not OK with it,” McCain said Friday, “but I think it’s better than shutting down the government.”

Added Collins: “I will vote for cloture. I’m still weighing [final passage] but I’m inclined toward it … The advantages of having a budget outweigh the reservations that I have.”

The last week of the budget fight has amounted to an unusual role reversal for the House and Senate. For much of this Congress, it’s been the Senate that’s passed bipartisan deals, only to see House Republicans balk. But this time around, House Republicans — who were burned by the last government shutdown — pushed the bipartisan deal through their chamber, only to see their GOP counterparts in the Senate scoff at the measure.

The differing views speak to the party’s continued divide over fiscal strategy as conservative groups rail against the measure, and senators up for reelection or eying higher office — such as Ted Cruz of Texas, Rand Paul of Kentucky and Marco Rubio of Florida — have all come out strongly against the plan.

The Senate developments come after the House gave overwhelming approval to the two-year budget bill Thursday evening, pushing the measure through on a resounding 332-94 bipartisan vote.

The big House vote appears to have convinced at least a handful of GOP senators to break a filibuster, but the margin is expected to be much narrower in the closely divided Senate.

Despite strong support from House Speaker John Boehner, Senate GOP leaders are expected to oppose the bill. GOP senators who are facing tea party-inspired challenges next year also are opposing the plan, including the defense hawk Lindsey Graham of South Carolina, who said the proposal would cause “disproportionate harm” to military retirees. And an increasing number of GOP senators began to lash out at the proposal.

Democrats were surprised when one of McCain’s like-minded colleagues, Kelly Ayotte of New Hampshire, announced she would oppose the bill. She — along with McCain and Graham — traveled the country last year warning of the dangers of the sequestration cuts to national security and was furious about the October government shutdown.

“I cannot support a budget agreement that fails to deal with the biggest drivers of our debt, but instead pays for more federal spending on the backs of our active duty and military retirees — those who have put their lives on the line to defend us,” Ayotte said.

An undecided Sen. Dan Coats (R-Ind.) added: “Does it begin to accomplish what a budget deal should accomplish?”

With Ayotte’s vote no longer in play, the focus shifts to several other potential “aye” votes, including Sens. Mark Kirk of Illinois and Murkowski.

The agreement, Murkowski said, “is weighing heavily on my mind as I leave the chamber on a Friday afernoon.”

Asked if she would vote to break a filibuster, Murkowski said: “I might.”

Corker said he could not support final passage of a bill that breaks budget caps that he has long sought to protect, but predicted at least five Republicans would vote to break the filibuster and said he’s considering doing so himself.

Supporters of the plan, drafted by Sen. Patty Murray (D-Wash.) and Rep. Paul Ryan (R-Wis.), are hoping some other Republican senators who periodically break ranks will vote in support of the agreement. GOP Sens. Rob Portman of Ohio, Lamar Alexander of Tennessee, Orrin Hatch of Utah and Hoeven are also seen as swing votes, though it’s unclear how they would come down.

But Senate Republicans are still weighing the policy implications and the political backlash from the right for supporting the deal— and they have the power to defeat it if they choose to unite against it. If they block the plan, it could make them culpable for any government shutdown that ensues in January as a result of the stalemate. But many Republicans in the Senate believe the plan is a bad deal that pushes off spending cuts without demanding more in return, agreeing with conservative activists who have come out against the proposal.

“No,” said Sen. Thad Cochran (R-Miss.), a veteran appropriator who is facing a primary challenge next year, when asked whether he had taken a position yet on the proposal.

Adding to the tension: Senate Republicans have been engaged in a tit-for-tat all week with Majority Leader Harry Reid after the Nevada Democrat’s unprecedented move to gut the filibuster on presidential nominees. Republicans have refused to let Reid quickly process those nominations, so Reid has kept the chamber in session overnight on consecutive days to work through the arcane Senate procedures.

In short, Republicans in the Senate are in no mood to cooperate with Reid.

“When hell freezes over” was Sen. Rand Paul’s (R-Ky.) prediction of when the GOP would cooperate with Reid’s unanimous-consent requests to quickly schedule action in the chamber. “The well has been poisoned.”

But Reid and Senate Minority Leader Mitch McConnell (R-Ky.) agreed on Friday to a series of votes that would spare lawmakers from further overnight sessions for the time being.

Despite the brief respite from the theatrics, McConnell is widely expected to oppose the budget measure, a position that could sway fence-sitting GOP senators. But it appears unlikely that GOP leaders would strong-arm their colleagues and urge them to oppose the budget.

Moreover, many Senate Republicans have raised deep concerns that the plan puts off spending cuts until the next decade when they may never be realized, echoing concerns of conservative outside groups who have been locked in a war of words with Boehner for much of this week.

If the proposal does not pass, discretionary spending would drop to $967 billion after Jan. 15, when another round of sequestration cuts reduces the Pentagon’s budget by $21 billion. But it would increase the risks of another government shutdown in January since the two chambers will not have agreed to top-line spending numbers.

The budget plan shifts about $63 billion in domestic and Pentagon sequestration cuts to other parts of the budget, including a 2 percent cut to Medicare providers in the next decade, cuts to federal workers’ pension programs, a reduction of cost-of-living adjustments for military retirees and an increase on airline fees paid to cover federal security costs. By doing that, overall discretionary spending would increase to $1.012 trillion in 2014, and $1.014 trillion the following fiscal year.

But to alleviate some concerns, Senate Armed Services Chairman Carl Levin (D-Mich.) announced Friday his panel would scrutinize the reductions in cost-of-living-adjustment payments to future military retirees before they would take effect in December 2015.

Boehner and House GOP leaders have argued that the plan actually would reduce the deficit by some $23 billion over the next decade, but Senate Republicans are skeptical.

“I have concerns about spending levels, busting the caps. The sequester actually caused a reduction in spending,” said Wyoming Sen. John Barrasso, the fourth-ranking Senate Republican.